Guiding and retaining mechanism for a bale wrapper

ABSTRACT

A machine is provided for wrapping film around a bale of agricultural product. The wrapping machine comprises of a table for receiving the bale and rotating the same about a horizontal axis. The design includes a dispenser unit for holding a roll of film and dispensing to the bale. There is a mechanism for rotating the dispenser unit relative to the bale about a second axis. An arm assembly is movable between a first position and a second position in which the arm assembly is capable of holding an end of the film. The arm assembly comprises a roller extending lengthwise. The stationary guide member prevents that film, which is screwed outwardly along the roller during the downward movement of the arm assembly, reaches the end of the same and hooks therebehind, such that the film is not torn before the next wrapping cycle is started.

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

Priority, and incorporation by reference, is hereby claimed under 35U.S.C. 119 to Great Britain Patent Application GB 04133336.9, titled“Guiding And Retaining Means For A Bale Wrapper”, filed Jun. 15, 2004,and having Karel O. R. Naeyaert and Danny N. O. Claeys as inventors.

FIELD OF INVENTION

The present invention relates to machines for wrapping sheet materialaround bales of agricultural products, such as silage. More particularlyit relates to mechanism for guiding and holding a slip of wrappingmaterial at the end of and between wrapping cycles.

BACKGROUND OF INVENTION

Machines for wrapping sheet material, such as coated plastic film,around bales of agricultural products are well known in the art. Theyare used for applying an airtight wrapping around the bale in order toprevent later ingress of air and to induce a fermentation process thatimproves the storing qualities of the product, which may be silagegrass, haylage, alfalfa or other. Most wrapping machines are designedfor wrapping cylindrical bales, which are produced by the so-calledround balers, but there also exist wrappers for rectangular bales, whichmay be made by large, high-density balers. A common type of wrappercomprises a stationary table, which rotates the bale about a horizontalaxis. While the bale is rotated, one or a pair of film dispensersapplies the film around the bale surface. The dispenser is mounted to asatellite arm, which is rotated about a central, upright axis in orderto revolve the dispenser around the bale. At the end of the wrappingcycle, a guiding and holding arm catches the film between the dispenserand the bale and the satellite arm is stopped. The arm guides the filmto a knife, which cuts the film loose from the bale. The free end of thefilm is pulled against the bale, but it is of no concern if a short endwould hang loose. The guiding and holding arm holds the other end of thefilm against a retainer. The wrapped bale is discharged from thewrapping machine, which is now ready for receiving a new bale. At thestart of the next wrapping cycle, the dispenser is rotated around thebale for at least one turn, while the end of the film is still beingheld against the retainer. When the film is secured against the bale byat least one overlapping layer of film, the guiding and holding arm willrelease the start end of the film, which is then caught between the baleand the newly dispensed film and finally disappears below thesubsequently applied film layers.

The wrapping machine in the baler-wrapper combination New Holland 548Combi™ is provided with two guiding and holding arm assemblies, whichare pivotable between an upper, film catching position, and a lower,film cutting and holding position. In the upper position, the armextends between the bale and the trajectory of the dispenser. After astrip of film has been pulled over the upright arm, the latter is moveddownwards to the knife and a holding pad. The arm should not tear thefilm apart prematurely, because a loose end of wrapping material wouldprevent a proper start of a new wrapping cycle as described above.Therefore, the arm comprises along its full length a roller, which ismounted for contacting and guiding the film strip. During downwardmovement of the arm, the roller is rotating along the coated filmsurface, which thereby gets no opportunity to stick permanently to theroll.

However, it has been experienced that for certain film qualities,especially for aged film, there is a tendency for the strip to migratealong the roll to its outer end. When the arm is in an inclined positionto the sheet film, the rotation of the roller along the surface willimpose an outward force upon the film and screw it outwardly. It ispossible that the upper border of the film strip finally reaches the endof the arm and hooks behind the extremity of the roll. The film startstearing and it is possible that it is damaged to the extent that it ispulled loose from the guiding and holding arm. Then there will be noconvenient starting end for the next bale and the operator will have tointervene in order to provide a new starting end between the arm and thedispenser and to restart the wrapper. Such operation is particularlytime-consuming as the operator has to interrupt the baling operations,stop the tractor and leave the tractor cab to refit the loose end ofwrapping material.

Accordingly, there is a need for guiding and holding mechanism, which onthe one hand smoothly guides the film material towards its holdposition, and on the other hand precludes an outward migration of thefilm over a distance longer than the length of the guiding and holdingmechanism itself.

SUMMARY OF INVENTION

According to the invention, there is provided a machine for wrappingsheet material around a bale of agricultural product, said machinecomprising: a table for receiving said bale and rotating the same abouta first axis; a dispenser unit for holding a roll of said sheet materialand dispensing said sheet material to said bale; mechanism for rotatingsaid dispenser unit relative to said bale about a second axis,substantially perpendicular to said first axis; and an arm assemblymovable between a first position in which said arm assembly extendsbetween said bale and the trajectory of said dispenser unit, and asecond position in which said arm assembly is capable of holding an endof said sheet material, said arm assembly comprising a roller extendinglengthwise of said arm assembly and capable of rotating around its axis,characterised in that said arm assembly further comprises a stationaryguide member, extending outwardly from said roller and positioned toreceive a border of said sheet material during the movement of said armassembly.

The stationary guide member prevents that sheet material, such as film,which is screwed outwardly along the roller during the downward movementof the arm assembly, reaches the end of the same and hooks there behind,such that the film is not torn before the next wrapping cycle isstarted.

Advantageously, the stationary member may comprise a cylindrical memberhaving substantially the same outer diameter as the rotatable roller.This structure provides a smooth transition for the film and reduces thechances of the film tearing when it reaches the stationary portion. Amember having a diameter that is slightly smaller than the roller, wouldequally be effective.

The member may be immobilised by a clamp that is installed between themember itself and a mechanism on the arm assembly for cutting the sheetmaterial at the end of a wrapping cycle. Such mechanism may comprise anelement that holds the sheet material against a knife blade. Theposition of this element may be adjustable in order to optimise thecutting action.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will no be described in furtherdetail, by way of example only, with reference to the accompanyingdrawings, in which:

FIG. 1 is a generally diagrammatic side view of baler-wrappercombination, comprising a wrapping machine according to the invention;

FIG. 2 is a somewhat simplified, perspective view of the wrappingmachine of FIG. 1, comprising a pair of guiding and holding mechanism;

FIG. 3 is a perspective view of one of the guiding and holding mechanismof FIG. 2 in a closed position;

FIG. 4 is an exploded view of the guiding and holding mechanism of FIG.3; and

FIG. 5 is a perspective view of the guiding and holding mechanism ofFIG. 3 in an open position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIEMENT

The machine shown in FIG. 1 is a baler-wrapper combination 1, comprisinga baler unit 2 and a wrapping unit 3, both mounted to a wheeled frame 4.The baler unit 4 shown is a round baler, provided with a pick-upassembly 5 for picking up crop material from a field and feeding it to acylindrical baling chamber 6. The crop material is collected andcompressed inside the baling chamber 6 to form a cylindrical bale, whichis stabilised by applying twine or net around its cylindrical periphery.Upon completion of the bale, the tailgate 7 of the baler unit 2 opens toenable transfer of the bale to the wrapper unit 3.

As shown in FIG. 2, the wrapper unit 3 is provided with a transfermechanism 9 for receiving the finished bale and transferring it to awrapping table 10. The transfer mechanism illustrated comprises a fork12, which is pivotable about a transverse axis 13 adjacent the front endof the wrapping table. It is also conceivable to use other transfermechanism such a horizontal belt or chain conveyor, or a shuttle table,which is placed below the open tailgate for receiving the bale and whichis moved backwards along a pair of rails or other convenient guidemechanism to transport the bale to the wrapping table 10.

The wrapping table 10 comprises a conveyor 15, e.g. a belt or chainconveyor, which extends between transverse front and rear axes 16,17.The bale is received and held on the top run of the conveyor 15.Operation of the conveyor makes the cylindrical bale rotate about itsown, horizontal axis. It is also possible to replace the conveyorassembly with a pair of transverse rollers, of which one or both aredriven to rotate the bale.

The wrapper unit 3 comprises an upper frame 19, affixed to the frame 4and extending above the area for the bale. The upper frame supports asatellite motor 20 from which extend a pair of satellite arms 21. Thesearms each support a film dispenser unit 22, which comprises a mechanismfor rotatably holding a roll 23 of wrapping film, and a prestretchermechanism for prestretching the film before it is applied to the surfaceof the bale. Such dispenser units are well known in the art and will notbe described in further detail. Commonly, the wrapper units are providedwith two dispenser units, but it is also possible to use a wrapperhaving only one dispenser unit.

During wrapping operations the satellite motor 20 is energised to rotatethe dispenser units 22 around the bale, while conveyor 15 of thewrapping table 10 rotates the bale around its horizontal axis. The filmfrom the roll 23 is prestretched and wrapped around the surface of thebale.

A guide and holding mechanism 25 is provided on each side of the wrapperunit 3. As shown in FIGS. 3 to 5, it comprises a movable arm assembly 26and a stationary cradle assembly 27. The latter assembly 27 comprises asupport bar 29 which is bolted to a horizontal beam of the frame 4 and aknife table 30, which is mounted by a transverse pivot bolt 31 to thesupport bar 29. This mounting allows some limited pivotment of the knifetable 30, when the arm assembly 26 comes to rest there against asdescribed hereinafter. The knife table 30 comprises a generally U-shapedprofile, which holds at its bottom a rubber pad 33, and a knife blade34, extending along substantially the full length of the knife table 30.The knife blade is securely held against an inner wall of the profile bya knife retainer 35. The outer tip of the knife is serrated in order toinduce a positive tearing of the wrapping film in this area.

The arm assembly 26 comprises a cylindrical rod 37, to which are weldedtwo downwardly extending lugs 38. The lugs are mounted on both sides ofa bearing 40, which is affixed to the support bar 29, and pivotablyconnected thereto by a pivot pin 39. A knife clamp 42 extends parallelto the rod 37 over its full length. It is mounted to the ends of the rod37 by a pair of bolts, which allow angular adjustment of the clamp 42about the rod axis. Most of the rod 37 is received in a roller 43, whichrotates freely about the rod itself. The roller is made out of plasticmaterial, but it also conceivable to use metal, as long as low-frictionrotation between the roller and the sustaining rod is made possible. Theouter section of the rod 37 carries a further cylindrical member 44.This member 44 has the same diameter and is made out of the samematerial as the roller 43. However, it is not permitted to rotate freelyabout the rod axis. To this end it is held in place by an angled clamp45, which is inserted between the knife clamp 42 and the cylindricalmember 44.

The arm assembly 26 can be moved between a substantially horizontalposition, as shown in FIG. 3, and an upright or angled position, asshown in FIG. 5, by a hydraulic cylinder 49. The rod end of the cylinder49 is connected by a pin 50 to the outer ends of the lugs 38 of the armassembly 49, and the chamber end is connected by a pin 51 to lugs 52,which extend downwardly from the support bar 29.

During wrapping operation the dispenser units 22 are rotated around thebale, which is rotated about its own axis by the conveyor 15 of thewrapping table 10. The material from the film rolls 23 is pulled throughthe pre-stretcher units, which extend the film and release more adhesivematerial to the film surface. The pre-stretched film is applied onto thesurface of the bale. During this phase the guide and holding mechanism25 are in their lower position, as shown in FIG. 3, such that there isno interference between the arm assembly 26 and the run of film betweenthe dispenser units 22 and on the bale.

When the bale is completely wrapped, the arm assembly 26 is raised tothe position of FIG. 5. At the next passage of the dispenser unit 22,the arm assembly 26 is caught by a stretch of film material. Thesatellite motor 20 is halted and the arm assembly 26 is lowered, therebypulling the film material downwardly towards the cradle assembly 27. Themovable roller 43 engages the coated side of the film and rotatestherealong while stretching the film somewhat further. The rotation ofthe roller 43 divides the forces on the film over the film sections onboth sides of the arm assembly 26, such that it does not reach itsstretch limit and does not start to tear apart. While the arm assembly26 pivots downwards, the upper edge of the film is screwed along therotating roller 43 towards the outer end of the rod 43. Eventually, thisedge reaches the stationary member 44. It still can slide along thismember 44 of the arm assembly 26, but the screwing action on this partof the film has stopped. Accordingly, there is no tendency anymore forthe upper strip of the film to migrate to the outer end of the rod 37and to get hooked behind the same. Further film material drivenoutwardly by the rotating roller 43, will be pushed against the haltedfilm border and start to wrinkle in the same area without breaking.

As the film edge is stopped adjacent the stationary member 44, it is notstretched as far as it would have been in case the roller 43 extendedover the full length of the arm assembly 26. Chances of tearing arethereby also reduced.

The arm assembly 26 finally arrives at its horizontal position, whereinit catches the film between the roller 43 and the rubber pad 33 of thecradle assembly 27. The knife clamp 42 pushes the film against the knifeblade 34, which tears the film and cuts the stretch between the cradleassembly 27 and the bale loose from the stretch between the cradleassembly 27 and the dispenser unit 27. The latter portion is kept inplace by the arm assembly 26, while the first portion is released andfloats against side surface the bale. Then the wrapping table 10 ispivoted rearwardly to deposit the wrapped bale onto the field.

The wrapping table 10 re-assumes its original, horizontal position andthe dispenser units 22 and the guide and holding mechanism 25 are heldstationary, until the transfer mechanism 9 load a fresh bale of cropmaterial on the wrapping table 10. Then, the wrapping table 10 and thesatellite arms 21 start to rotate at a slow speed. The dispenser units22 dispense the film around the bale, while the outer slip of the filmis still being held against the rubber pad 33. The presence of awrinkled film section near the upper border improves it resistanceagainst tearing during this phase. When the dispenser units 22 havecompleted at least one revolution, the cylinders 49 raise the armassemblies 27 for a short period in order to release the film end.Thereafter the arm assemblies 27 are lowered again to preventinterference with the newly applied film or with the rotating dispenserunits 22. The satellite motor 20 is then driven at full speed forwrapping the remainder of the bale surface. The slip of film materialwhich has been released from the guide and holding mechanism 25, floatsagainst the bale surface and is covered by the subsequent layers offilm.

Hence, there is provided a guiding and holding mechanism 25 that iscapable of guiding the film material smoothly to a holding position andwhich is not prone to defective operation caused by the tearing of saidfilm during said guiding operation. The rotatable guide roller 43 allowsrelative movement between the film and the guiding mechanism, therebyprecluding excess local tensions that would break the film, and theouter stationary member portion limits the movement of the film to alocation where it hooks behind the guiding mechanism itself.

Although the present invention has been described with reference to aparticular wrapping machine, it should be understood that the inventionis not limited to this particular embodiment. Other embodiments can bethought of without departing from the scope of the invention as definedby the claims. For instance, the invention may equally be applied in anindependent wrapping machine, which is not linked to a baler. It mayalso be used in a wrapping machine of the type using one or twostationary dispensers and a wrapping table that rotates about a central,upright axis. The stationary member at the outer end of the rod mayequally be secured by conventional connection mechanism such as bolts orglue.

1. A machine for wrapping sheet material around a bale of agriculturalproduct, said machine comprising: a table for receiving said bale androtating the same about a first axis; a dispenser unit for holding aroll of said sheet material and dispensing said sheet material to saidbale; mechanism for rotating said dispenser unit relative to said baleabout a second axis, substantially perpendicular to said first axis; andan arm assembly movable between a first position in which said armassembly extends between said bale and the trajectory of said dispenserunit, and a second position in which said arm assembly is capable ofholding an end of said sheet material, said arm assembly comprising aroller extending lengthwise of said arm assembly and capable of rotatingaround its axis, characterised in that said arm assembly furthercomprises a stationary guide member, extending outwardly from saidroller and positioned to receive a border of said sheet material duringthe movement of said arm assembly.
 2. A machine according to claim 1,characterised in that said stationary guide member comprises acylindrical member, having substantially the same outer diameter as saidrotatable roller.
 3. A machine according to claim 1, characterised inthat said stationary guide member comprises a cylindrical member, havingan outer diameter slightly smaller than said rotatable roller.
 4. Amachine according to claim 3, characterised in that said cylindricalmember is held stationary by a clamp installed between said cylindricalmember and a mechanism installed on said arm assembly for cutting saidsheet material.
 5. A machine according to claim 4, characterised in thatsaid arm assembly is mounted for pivotment about a substantiallyhorizontal axis.
 6. A machine according to claim 1, characterised inthat said first position is an upright or inclined position and saidsecond position is a horizontal position.
 7. A machine according toclaim 1, characterised in that, in said second position, said armassembly is positioned adjacent a cutting mechanism.
 8. A machineaccording to claim 6, characterised in that, in said second position,said arm assembly is positioned adjacent a cutting mechanism.
 9. Amachine according to claim 8, characterised in that the machine ismounted to the rear end of a baler unit.
 10. A machine according toclaim 9, characterised in that said mechanism for rotating saiddispenser unit comprise a satellite arm which is mounted for rotationabout an upright axis and motor mechanism for rotating said satellitearm.